Fluid circulation pump

ABSTRACT

A fluid flow pump comprising a suction inlet, a discharge outlet, and a movable part inside the chamber. The pump includes circular first upstream and downstream lips such that: over a first portion of the movement of said movable part in the chamber, the circular first upstream lip then allowing free passage for fluid between the first space and the suction inlet; and that over a second portion of said movement, the circular first upstream lip provides sealing preventing fluid from passing to the suction inlet, the circular first downstream lip allowing fluid to pass from the first space to said discharge outlet and preventing fluid from passing to said first space.

The present invention relates to the field of fluid flow pumps.

BACKGROUND OF THE INVENTION

Pumps are known that are provided with a chamber of volume that varies as a function of the movement of a part that is movable inside the chamber, the chamber being fitted with a checkvalve upstream from the chamber and with a checkvalve downstream from the chamber.

When the volume of the chamber increases, the chamber is then in the suction, so the upstream checkvalve opens and the downstream checkvalve closes, with the fluid then being sucked into the chamber.

When the volume of the chamber decreases, the chamber is then in compression, so the upstream checkvalve closes and the downstream checkvalve opens, with the fluid then being discharged from the chamber to a discharge outlet.

Such checkvalves are parts that are subject to wear and that give rise to head loss.

OBJECT OF THE INVENTION

An object of the present invention is to provide a fluid flow pump that causes fluid to flow and that minimizes head loss.

SUMMARY OF THE INVENTION

To this end, the invention provides a fluid flow pump comprising a suction inlet, a discharge outlet, a chamber in fluid flow connection with the suction inlet and with the discharge outlet, a movable part arranged inside the chamber, and at least one motor mechanically connected to the movable part to move it inside the chamber.

The pump of the invention is essentially characterized in that it includes a circular first upstream lip placed closer to the suction inlet than to the discharge outlet and a circular first downstream lip placed closer to the discharge outlet than to the suction inlet, these circular first upstream and downstream lips being placed between one of the sides of said movable part and a first wall of the chamber to define a first space between the circular first upstream and downstream lips, these circular first upstream and downstream lips being such that:

-   -   over a first portion of said movement of said movable part         relative to the chamber, the circular first downstream lip         provides sealing preventing fluid from passing from said         discharge outlet to said first space, the circular first         upstream lip then allowing free passage for fluid between said         first space and said suction inlet; and that     -   over a second portion of said reciprocating motion of said         movable part relative to the chamber, different from the first         portion of the movement, the circular first upstream lip         provides sealing preventing fluid from passing from said first         space to said suction inlet, the circular first downstream lip         being arranged so that throughout said movement of said movable         part relative to the chamber:     -   it allows fluid to pass from the first space to said discharge         outlet; and     -   it prevents fluid from passing from said discharge outlet to         said first space.

In order to understand the invention, the first and second portions of the movement of said movable part relative to the chamber are distinct from each other, i.e. the positions respectively adopted by the movable part over the first portion of the movement are all different from the positions respectively adopted by the movable part over the second portion of the movement.

By means of this arrangement of the pump of the invention, the movable part causes the volume of the first space to vary in such a manner that the first space is:

-   -   either in suction and open towards the fluid suction inlet for         sucking fluid into the space (the discharge outlet then being         closed by the first downstream lip);     -   or else in compression and open only towards the discharge         outlet in order to discharge the fluid from the first space to         the discharge outlet (the suction inlet then being closed by the         first upstream lip).

Since over the first portion of said movement of said movable part relative to the chamber, the circular first upstream lip allows free passage for fluid between said first space and said suction inlet, it gives rise to limited head loss while admitting fluid into the chamber.

Thus, unlike prior art pumps that require an admission checkvalve, the pump of the invention can operate without such an admission checkvalve. The efficiency of the pump is thus improved during its stage of admitting fluid into the chamber.

The pump of the invention is thus particularly effective in transferring a fluid, which fluid may be a gas or a liquid.

By limiting head loss during admission, the dry self-priming ability of the pump is thus improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention appear clearly from the following description that is given by way of nonlimiting indication and with reference to the accompanying drawings, in which:

FIG. 1a is a cross-section view of a pump 100 of the invention that includes an electric motor 46 driving a movable part 45 with reciprocating motion between first and second walls 44 a and 44 b of the chamber 44 in order to cause the pump to suck in fluid; a portion of FIG. 1a is an enlargement of the movable part 45 in which there can be seen circular first upstream and downstream lips 120 a and 121 a on a first side of the part 45, and circular second upstream and downstream lips 120 b and 121 b on another side of the part 45;

FIG. 1b is a detail view of the lips in a section plane in which there extends an axis of symmetry X-X of the lips, it can be seen that each of the first upstream and downstream lips presents a thickness E that is constant over a major fraction of the length of the lip, with each of these lips being chamfered at its terminal end (the chamfer increases the contact area of the lip and improves its sealing and its lifetime);

FIG. 2 is a view of a pump of the invention in which the movable part 45 is a tube that is radially expandable relative to an axis of symmetry X-X of the lips, FIG. 2 being observed in a section plane in which said axis of symmetry X-X of the lips extends;

FIG. 3 is a view of the pump of the invention as shown in FIG. 2, while it is being put into operation under drive from the electric motor 46;

FIG. 4 is a section view of a pump similar to the pump in FIGS. 2 and 3, but in which the lips are not carried by the walls 44 a and 44 b of the chamber 44, but are carried by the movable part 45, which is tubular and radially deformable about the axis of symmetry X-X;

FIG. 5 is a detail view of the lips and of the movable part 45 of the pump of the invention as shown in FIG. 1a , this view showing the movable part 45 in a first portion P1 of its movement, the pump then being in suction with a free fluid passage created by the upstream lip 120 a;

FIG. 6 is a detail view similar to FIG. 5, but in which the pump is discharging, with an open fluid passage going past the downstream lip 121 a;

FIG. 7 is a section view of the movable part 45 in the chamber 44, the first lips 120 a and 121 a being shown attached to a first side of the movable part 45 so as to bear against a first wall 44 a of the chamber 44 and the second lips 120 b and 121 b being shown attached to a second side of the movable part 45 so as to bear against a second wall 44 b of the chamber 44;

FIG. 8 is a section view of the second wall 44 b of the chamber 40 of the pump, and in this embodiment the second lips 120 b and 121 b are not attached to the movable part 45 as they are in FIG. 7, but they are attached exclusively to the second wall 44 b of the chamber 44 (this embodiment is like the embodiment shown in FIG. 1a in which the second wall 44 b carries the second lips 120 b and 121 b and in which the first wall 44 a carries the first lips 120 a and 121 a); and

FIG. 9 is a perspective view of a portion of the pump of the invention in an embodiment in which the movable part is in the form of a strip and in which the first upstream and downstream lips 120 a and 121 a and the second upstream and downstream lips 120 b and 121 b are rectilinear.

DETAILED DESCRIPTION OF THE INVENTION

As mentioned above, the pump 100 of the invention includes a suction inlet 41 and a discharge outlet 42.

The pump includes a motor 46 that may be located either outside the chamber 44, as shown in FIG. 1a , or else inside the chamber, as shown in FIGS. 2 to 4.

In all embodiments, the motor 46 is mechanically connected to the movable part in order to be able to move it inside the chamber 44.

The pump 100 also has a first upstream lip 120 a that is placed closer to the suction inlet 41 than it is to the discharge outlet 42, and a first downstream lip 121 a that is placed closer to the discharge outlet 42 that it is to the suction inlet 41.

These first upstream and downstream lips 120 a and 121 a are placed between one of the sides of said movable part 45 and a first wall 44 a of the chamber 44 so as to define a first space 123 a between these first upstream and downstream lips 120 a and 121 a.

The arrangement of the lips defining the first passage 123 a gives the pump the ability to be self-priming when dry.

A pump is said to be “self-priming when dry” when the pump can suck in dry air and can create sufficient suction to suck in liquid and move the liquid into the chamber in order to discharge it via a discharge outlet 42 of the pump.

These first upstream and downstream lips 120 a and 121 a are preferably circular, with the movable part 45 then being in the shape of a disk, as shown in FIGS. 1a, 1b , 5, 6, 7, and 8, or else in the shape of a tube (as shown in FIGS. 2, 3, and 4).

Nevertheless, these first upstream and downstream lips 120 a and 121 a could also be rectilinear, as shown in FIG. 9, with the movable part 45 then being in the shape of a strip (as in FIG. 9), which part 45 may be rigid or elastically deformable depending on the length of the strip.

As can be seen in FIG. 1a , the pump 100 is connected to a control unit UC of the pump 100, which is adapted to control the supply of electrical power to the motor 46 of the pump 100.

Preferably, the control unit UC is arranged to regulate the operation of the motor 46 as a function of at least one value that has previously been estimated by the control unit.

This at least one value that has previously been estimated by the control unit UC may be a value estimated by at least one sensor and/or probe 50.

This at least one previously-estimated value may be a value for the pressure of the fluid driven by the pump, a value for the flow rate of the fluid driven by the pump, a value for the speed of movement of the motor, a value for the frequency of movement of the motor, a value representative of a movement amplitude of the movable part 5, and/or a value representative of a position of the movable part 5.

The motor 46, in this example an electric motor, and the control unit UC are powered via an electric power cable 60.

The control unit UC may itself be connected to a probe 50 that is adapted to detect when a liquid level is reached relative to the pump 100. Under such circumstances, the control unit UC is arranged to control the supply of electric power to the motor in response to the probe 50 detecting said liquid level.

The probe 50 may be fastened to the pump, or alternatively it may be fastened to an element other than the pump.

The probe 50 may be adjustable so as to adjust the detection level from which the probe detects the presence of liquid on a floor on which the pump is arranged.

As shown in FIG. 1a , the probe 50 may comprise at least two electrodes 51 that are spaced apart from each other so as to be able to detect when a liquid level is reached as a function of these electrodes measuring at least one electrical characteristic.

This electrical characteristic must vary depending on the nature of the fluid that is to be found between the electrodes.

For example, the electrical characteristic measured by means of the electrodes may be an electric resistance between electrodes, an electric current between the electrodes, or an electric voltage between the electrodes.

Thus, as soon as the liquid comes into contact with the electrodes, there is a change in the measured electrical characteristic, and it is thus possible to detect that the liquid level has been reached.

As a function of this detection, the control unit UC causes the electric motor 46 to operate.

This serves to avoid causing the motor to operate for liquid levels that are too shallow, with the pump being actuated only when it can begin to suck in the liquid on the floor.

A timeout may also be used in order to allow the pump to continue to operate after the probe detects that the fluid is absent. This serves to avoid repeated stopping and starting of the pump. This improves the lifetime of the pump.

As can be understood from FIGS. 1a , 2, 3, 4, 5, and 6, the electric motor 46 is connected to the movable part 45 by a coupling mechanism 52 is such a manner that the control unit UC actuating the electric motor 46 causes the movable part 45 to perform reciprocating motion relative to the chamber in order to move a fluid (a gas or a liquid) from the suction inlet 41 to the discharge outlet 42.

In FIGS. 1a, 1b , 5, and 6, the movable part 45 is in the shape of a disk that is hollow in its center and that is connected to the electric motor in such a manner as to be moved with rectilinear reciprocating motion in a direction perpendicular to the plane in which the disk extends.

The first space 123 a defined between the lips 120 a and 121 a forms an angular space extending between a first wall 44 a of the chamber 44 and a first side of the movable part 45 that faces this first wall 44 a.

The hollow in the center of the disk enables a pumping effect to be obtained on both sides of the movable part with only one discharge outlet facing the hollow.

Nevertheless, it is possible to envisage the movable part 45 being a solid disk (without a hollow in its center), in which case the movable part 45 is capable of:

-   -   either producing a pumping effect on only one of its two sides         (in which case there needs to be only one discharge outlet);     -   or else of producing a pumping effect on both of its sides (in         which case it is necessary to provide respective discharge         outlets for each of the sides of the movable part).

In this example, the movable part 45 is rigid, however it could be deformable in such a manner that actuating the electric motor 46 gives rise to a wave that propagates radially across the movable part 45 in order to move the fluid.

Under such circumstances, the movable part 45 may comprise an elastically deformable diaphragm so as to permit propagation of a wave supported by the diaphragm, with the diaphragm being referred to as an undulating diaphragm.

In particular embodiments, the diaphragm may be in the shape of a disk (the wave propagating radially relative to the disk) or in the shape of a strip (the wave propagating along the length of the strip) or, as shown in FIGS. 2 to 4, in the shape of an elongate flexible tube that is peripherally stretchable (in which case the wave is a circular wave formed in the periphery of the tube and propagating along the length of the tube).

In all the embodiments of the pump of the invention, the first upstream lip 120 a (which is circular when the diaphragm is in the shape of a disk or of a tube, and which is rectilinear when the diaphragm is in the shape of a strip) and the first downstream lip 121 a (which is circular when the diaphragm is the shape of a disk or of tube, and which is rectilinear when the diaphragm is the shape of a strip) are designed to deform as a function of the motion of the movable part 45 in such a manner as to create a first space 123 a between the lips 120 a and 121 a and the wall 44 a of the chamber 44, which first space 123 a alternates between:

-   -   expanding when the movable part 45 is moving away from the first         wall 44 a the chamber; and     -   compressing when the movable part 45 is moving towards the first         wall 44 a.

The part 45 is moved by the motor 46 so as to alternate between moving away from the first wall 44 a and moving towards it.

Over a first portion P1 of the reciprocating motion of said movable part 45 relative to the chamber 44, the circular upstream lip 120 a is always spaced apart from the first wall 44 a, thereby providing a free passage between the first space 123 a and the suction inlet 41.

Over this first portion P1 of said reciprocating motion of said movable part 45 relative to the chamber 44, the circular upstream lip 120 a allows fluid to pass freely between the suction inlet 41 and the space 123 a, regardless of the fluid pressure difference between the space 123 a and the suction inlet 41.

Over a second portion P2 of said reciprocating motion of said movable part 45, which is different from the first portion P1 of the motion, the circular upstream lip 120 a:

-   -   firstly allows fluid to pass from the suction inlet to the space         123 a only if the pressure of the fluid upstream from the         upstream lip 120 a exceeds the pressure of the fluid in the         space 123 a by some predetermined minimum difference value; and     -   a secondly prevents fluid from passing from the first space 123         a to the suction inlet.

Furthermore, throughout the motion of said movable part 45 relative to the chamber 44, the downstream lip 121 a is adapted:

-   -   firstly to create sealing contact against the first wall 44 a so         long as the pressure of the fluid in the space 123 a is lower         than the pressure of the fluid downstream from the downstream         lip 121 a; and     -   secondly to move away from the first wall 44 a when the pressure         of the fluid in the space 123 a is higher than the pressure of         the fluid downstream from the downstream lip 121 a.

In other words, throughout the motion of said movable part 45 relative to the chamber 44, the circular first downstream lip 121 a:

-   -   allows fluid to pass from the first space 123 a to said         discharge outlet 42; and     -   prevents fluid from passing from said discharge outlet 42 to         said first space 123 a.

Thus, the space 123 a alternates between being in suction and open to the suction inlet 41 in order to suck in the fluid (gas or liquid) therefrom, and being in compression and open to the discharge outlet 42 in order to expel the fluid therethrough.

These circular upstream and downstream lips 120 a and 121 a enable the pump or to be self-priming.

The reciprocating motion of the movable part 45 causes fluid to be sucked from the suction inlet 41 into the first space 123 a during the first portion P1 of the motion, and then causes the fluid to be expelled from the first space 123 a to the discharge outlet 42 over the second portion P2 of said reciprocating motion.

In order to double this suction/expulsion effect on the fluid/liquid, and as shown in the embodiments of FIGS. 1a , 2, 3, 4, 5, 6, and 7, provision can be made for the pump to include a second upstream lip 120 b and a second downstream lip 121 b that are designed to deform as a function of the motion of the movable part 45 in such a manner as to create second space 123 b between these lips 120 b and 121 b and a second wall 44 b of the chamber 44, which second space 123 b:

-   -   expands when the movable part 45 is moving away from the second         wall 44 b the chamber; and     -   compresses when the movable part 45 is moving towards the second         wall 44 b.

Specifically, the part 45 is movable between the first and second walls 44 a and 44 b of the chamber 44.

While it is being moved by the motor, the part 45 alternates between being moved away from and towards the second wall 44 b.

These second upstream and downstream lips 120 b and 121 b are preferably circular, with the movable part 45 then being in the shape of a disk, (as shown in FIGS. 1a, 1b , 5, 6, 7, and 8), or else tubular (as shown in FIGS. 2, 3, and 4).

Nevertheless, these second upstream and downstream lips 120 b and 121 b could be rectilinear, as shown in FIG. 9, with the movable part 45 then being in the shape of a strip (as in FIG. 9), which part 45 may be rigid or elastically deformable along the length of the strip.

The second upstream lip 120 b is placed closer to the suction inlet 41 than it is to the discharge outlet 42, and a second downstream lip 121 b is placed closer to the discharge outlet 42 that it is to the suction inlet 41.

These second upstream and downstream lips 120 b and 121 b are placed between one of the sides of said movable part 45 and a second wall 44 b of the chamber 44 so as to define a second space 123 b between these second upstream and downstream lips 120 b and 121 b.

The second upstream lip 120 b is adapted so that over a third portion of said reciprocating motion of said movable part 45 relative to the chamber 44, the second upstream lip 120 b allows free passage for the fluid between said second space 123 b and said suction inlet 41.

In other words, this second upstream lip 120 b is of dimensions such that over the entire third portion of said reciprocating motion of said movable part 45 relative to the chamber 44, the second upstream lip 120 b is spaced apart from the second wall 44 b.

Preferably, this third portion of the motion corresponds to said second portion of the motion.

The second upstream lip 120 b is also adapted so that throughout a fourth portion of said motion of said movable part 45 relative to the chamber 44, the second upstream lip 120 b:

-   -   creates sealing contact against the second wall 44 b so long as         the pressure of fluid in the second space 123 b is higher than         the pressure of fluid upstream from the second upstream lip 120         b; and     -   allows fluid to pass from the suction inlet 41 to the second         space 123 b when the pressure of fluid upstream from the second         upstream lip 120 b is higher than the pressure of fluid in the         second space 123 b.

Preferably, this fourth portion of the motion corresponds to said first portion of the motion of the part 45.

Throughout said motion of said movable part 45 relative to the chamber 44, the second downstream lip 121 b is adapted:

-   -   to create sealing contact against the second wall 44 b so long         as the pressure of fluid in the second space 123 b is lower than         the pressure of fluid downstream from the second downstream lip         121 b; and     -   to move away from the second wall 44 b when the pressure of the         fluid in the space 123 b is higher than the pressure of the         fluid downstream from the downstream lip 121 b.

Thus, the second space 123 b alternates between being in suction and open to the suction inlet 41 in order to suck in the fluid (gas or liquid) therefrom, and being in compression and open to the discharge outlet 42 in order to expel the fluid therethrough.

In the example of FIGS. 1a , 5, 6, and 7, since the movable part 45 is in the shape of a disk that is hollow in its center, the second space 123 b forms an annular space extending between the second wall 44 b and the second side of the movable part 45 that is facing the second wall 44 b. In these embodiments of FIGS. 1a , 5, 6, and 7, the second upstream and downstream lips 120 a and 121 b are circular.

As can be understood in particular from FIG. 1a , these second upstream and downstream lips 120 b and 121 b are such that over the third portion of said reciprocating motion of said movable part 45 relative to the chamber 44, the second downstream lip 121 b provides sealing that prevents fluid from passing from said discharge outlet 42 to said second space 123 b, with the second upstream lip 120 b then allowing free passage for fluid between said second space 123 b and said suction inlet 41.

Over this third portion of said reciprocating motion of said movable part 45, the second upstream lip 120 b is spaced apart from one of said second wall 44 b and movable part 45 in order to generate a free fluid passage, i.e. a free space between said second space 123 b and said suction inlet 41.

Thus, over this third portion of said reciprocating motion, since the second space 123 b is closed downstream and open upstream, a fluid suction effect is obtained from the suction inlet 41 towards the second space 123 b by spacing the movable part 45 away from the second wall 44 b.

As can be understood in particular from FIGS. 1 to 7, these circular second upstream and downstream lips 120 b and 121 b are such that over the fourth portion of said reciprocating motion of said movable part 45 relative to the chamber 44, the second upstream lip 120 b provides sealing that prevents fluid from passing from said second space 123 b to said suction inlet 41, with the second downstream lip 121 b then being arranged:

-   -   firstly to allow fluid to pass between said second space 123 b         and said discharge outlet 42 when the fluid pressure inside said         second space 123 b is higher than the fluid pressure at the         discharge outlet 42; and     -   secondly to prevent fluid from passing from said discharge         outlet 42 to said second space 123 b.

Thus, over this fourth portion of said reciprocating motion, since the second space 123 b is closed upstream and open downstream only when the fluid pressure in the second space 123 b is higher than the fluid pressure at the discharge outlet 42, fluid is discharged from the second space 123 b to the discharge outlet 42 by moving the movable part 45 towards the second wall 44 b.

The reciprocating motion of the movable part 45 causes fluid to be sucked from the suction inlet 41 into the second space 123 a and then causes the fluid to be expelled from the second space 123 b to the discharge outlet 42.

Thus, by means of the pairs of lips placed on either side of the part 45, two suctions and two discharges occur over one cycle of the motion of the part 45, thereby enabling a fluid flow to be obtained that is more uniform over time.

It should be observed that the number of lips facing each face of the movable part 45 could be different.

Thus, if one of the faces of the movable part does not have any facing lip, then that is either because that face is not used for pumping (as applies to a movable part in the form of a disk without a hollow center), or else because it is the movable part 45 that is deformable in order to establish sealing against the corresponding wall of the chamber.

Using only one lip on a side of the movable part serves only to oppose fluid return.

Using two lips on a side of the movable part 45 serves to create the space between an upstream lip and a downstream lip in order to obtain a pump presenting a self-priming effect when dry.

With more than two lips on the same side of the movable part 45, a greater pressure difference is generated between the discharge outlet and the suction inlet of the pump.

Thus, depending on the desired pressure difference, it is possible to have three lips on each side of the movable part, or even more.

Under certain conditions, it has been observed that a given lip can become pressed against a support of the lip (the chamber wall or the movable part) and act as a suction cup.

The behavior of the pump 100 is then degraded, since that given lip no longer performs its sealing function.

In order to avoid that, and as shown in FIGS. 1, 5, 6, 7, and 8, it is ensured that at least one fluid passage 48, 49 is created between the given lip and its support 124.

Each at least one fluid passage 48, 49 between a given lip and its support 124 is such that when the lip comes to pressed against its support, fluid can continue to flow between the lip and its support. This avoids the suction cup effect.

To do this, it is possible either to create shape irregularities between the given lip and its support, such as:

-   -   projections 48 carried by the given lip and extending towards         its support; and/or     -   projections carried by the support 124 and extending towards the         given lip that it supports; and/or     -   channels (hollow zones) carried by the given lip and extending         towards its support 124; and/or     -   channels 49 (hollow zones) carried by the support 124 and         extending towards the given lip that it supports.

Preferably, each projection 48 or channel 49 extends longitudinally from one end of the given lip towards a junction point between that lip and its support.

It is generally preferable for the projections and/or channels to be formed/carried solely by the support 124 of the lip rather than by the lip itself, since the lip is then deformable in uniform manner.

Having a projection or a channel carried by a given lip gives rise to preferred deformation zones over the lip, which can then give rise to losses of sealing that are detrimental to the operation of the pump 100.

When the given lip is annular and/or circular, it is preferable for the projections or channels to be formed on the support of the lip so as to form radii centered around an axis of symmetry of the given lip.

Under such circumstances, said at least one fluid passage 48, 49 formed between the given lip and its support 124 extends radially relative to a central axis of symmetry X-X of the at least one given lip.

When the given lip is rectilinear, as in FIG. 9, it is preferred to form rectilinear projections or channels on the support of the lip, these projections or channels being perpendicular to the lip.

As can be seen in FIGS. 1b to 8, when observed in a section plane containing a central axis of symmetry (X-X) that is common to said lips, each of said lips has a specific section extending over a major portion of the length of the given lip, this specific section of the lip being of constant thickness E in the section plane.

Thus, the specific section of constant thickness E of a given lip extends over a major portion of the length of the given lip when seen in said section plane containing the axes of symmetry X-X of the lip.

The thickness of a specific section of a given lip is considered to be constant providing the minimum thickness of the lip as measured in the specific section is greater than 70% of the maximum thickness of the lip measured in the specific section.

The constant specific thicknesses E of the upstream lips 120 a and 120 b are preferably identical to each other.

Likewise, the constant specific thicknesses E of the downstream lips 121 a and 121 b are preferably identical to each other.

It should be observed that the constant specific thicknesses E of the upstream lips 120 a and 120 b are preferably greater than the constant specific thicknesses E of the downstream lips 121 a and 121 b.

The length of a given lip is the distance measured between an attachment point where the given lip is attached to its support 124 and an end point of the given lip, these attachment and end points being observed in the section plane containing the central axis of symmetry X-X.

Preferably, when observed in said section plane, each of the lips has a chamfered end, the chamfer constituting a sealing surface for alternately pressing to provide sealing and being spaced apart to allow the fluid to pass.

The chamfered end increases the sealing surface area of the lip and improves its strength (even if the chamfered portion should present a damaged zone, it would continue to be capable of providing sealing selectively all around the damaged zone).

Preferably, in said circular first upstream lip 120 a presents a conical inside surface facing towards a central axis of symmetry X-X of the circular first upstream lip 120 a, the conical inside surface extending between a circular base of the circular first upstream lip 120 a and a circular end of the circular first upstream lip 120 a.

The conical inside surface of a given lip that extends between a circular base of the given lip and a circular end of the given lip serves to minimize the inside surface area of the lip that is exposed to the fluid under pressure.

By reducing this surface area that is exposed to the fluid under pressure, any risk of the given lip bulging outwards under the effect of the fluid is limited.

Such a conical inside surface makes it possible to increase the maximum pressure that can be generated by the pump.

To do this, it is preferable for said circular second upstream lip 120 b also to present a conical inside surface facing towards a central axis of symmetry X-X of the circular second upstream lip 120 b. This conical inside surface of the circular second upstream lip 120 b extends between a circular base of the upstream second circular lip 120 b and a circular end of the circular second upstream lip 120 b.

For the same reason, it is preferable for each circular downstream lip 121 a, 121 b to present a conical inside surface facing towards a central axis of symmetry X-X of the circular downstream lip 121 a, 121 b.

This conical inside surface of the circular downstream lip 121 a, 121 b extends between a circular base of the circular downstream lip 121 a, 121 b and a circular end of the circular downstream lip 121 a, 121 b.

Preferably, each conical inside surface of any given one of the circular lips 120 a, 121 a, 120 b, or 121 b presents a cone angle that is less than or equal to 40° relative to a plane in which the circular base of the given circular lip extends.

Having a cone angle that is less than or equal to 40° serves, during the movement of the movable part 45 relative to the wall of the chamber, to maximize radial deformation of the lip while minimizing its axial deformation along the axis X-X. Thus, the force from the lip opposing movement of the movable part is minimized and wear of the lip is reduced.

Preferably, each of said lips 120 a, 120 b, 121 a, and 121 b is made of a material that presents a Young's modulus lying in the range 1 mega pascal (MPa) to 220 MPa.

Thus, the lip presents a compromise that accommodates the bending needed for the movable part 45 to move, while also limiting its radial deformation under the effect of the fluid pressure.

In each of the embodiments shown in FIGS. 1, 1 b, 2, 3, 5, 6, 8, and 12 the circular first upstream and downstream lips 120 a and 121 a are carried by a base that is common to those lips, which base is releasably assembled on the first wall 44 a of the chamber 44.

In similar manner, the circular first upstream and downstream lips 120 b and 121 b are carried by a base that is common to those lips, which base is releasably assembled on the second wall 44 b of the chamber 44.

Thus, the lips can be replaced together by removing the bases that carry them.

Alternatively, and as shown in FIGS. 4 and 7, the first upstream and downstream lips 120 a and 121 a may be carried by said movable part 45.

In the same manner as described above, a common base for those lips may be releasably assembled on the movable part 45.

This embodiment enables the lips 120 a and 121 a to be replaced independently of the movable part 45.

As shown in figures a, 1 b, 5, 6, and 7, the reciprocating motion of the movable part 45 may be axial motion along a central axis of symmetry X-X of the movable part 45, which is in the shape of a body of revolution.

Alternatively, as shown in FIGS. 2 and 4, the reciprocating motion of the movable part (45) may be radial motion about a central axis of symmetry X-X of the movable part 45, which is in the shape of a body of revolution.

The motor 46 may be located inside the chamber, as in FIGS. 2, 3, and 4, or it may be located outside the chamber, as in FIGS. 1a , 5, and 6. 

1. A fluid flow pump comprising a suction inlet, a discharge outlet, a chamber in fluid flow connection with the suction inlet and with the discharge outlet, a movable part arranged inside the chamber, and at least one motor mechanically connected to the movable part to move it inside the chamber, the pump being wherein it includes a first upstream lip placed closer to the suction inlet than to the discharge outlet and a first downstream lip placed closer to the discharge outlet than to the suction inlet, these first upstream and downstream lips being placed between one of the sides of said movable part and a first wall of the chamber to define a first space between the first upstream and downstream lips, these first upstream and downstream lips being such that: over a first portion of said movement of said movable part relative to the chamber, the first downstream lip provides sealing preventing fluid from passing from said discharge outlet to said first space, the first upstream lip being always spaced apart from the first wall then allowing free passage for fluid between said first space and said suction inlet; and that over a second portion of said reciprocating motion of said movable part relative to the chamber, different from the first portion of the movement, the first upstream lip provides sealing preventing fluid from passing from said first space to said suction inlet, the first downstream lip being arranged so that throughout said movement of said movable part relative to the chamber: it allows fluid to pass from the first space to said discharge outlet; and it prevents fluid from passing from said discharge outlet to said first space.
 2. The pump according to claim 1, wherein at least one of said lips is carried by a support, at least one fluid passage being formed between this at least one given lip and its support, the at least one fluid passage being such that when said at least one given lip bears against its support, fluid can flow via said at least one fluid passage between the at least one given lip and its support.
 3. The pump according to claim 2, wherein said at least one fluid passage formed between said at least one given lip and its support is formed along a projection carried by the support.
 4. The pump according to claim 2, wherein said at least one fluid passage formed between said at least one given lip and its support is formed along a projection carried by said at least one given lip.
 5. The pump according to claim 2, wherein said at least one fluid passage formed between said at least one given lip and its support is a channel carried by the support.
 6. The pump according to claim 2, wherein said at least one fluid passage formed between said at least one given lip and its support is a channel carried by said at least one given lip.
 7. The pump according to claim 2, wherein said at least one fluid passage formed between said at least one given lip and its support extends radially relative to a central axis of symmetry of said at least one given lip.
 8. The pump according to claim 1, wherein when observed in a section plane containing a central axis of symmetry that is common to said lips, each of said lips has a specific section extending over a major portion of the length of the given lip, this specific section of the lip being of constant thickness in the section plane.
 9. The pump according to claim 1, wherein said first upstream lip is a circular lip that presents a conical inside surface facing towards a central axis of symmetry of the first upstream lip, the conical inside surface extending between a circular base of the first upstream lip and a circular end of the first upstream lip.
 10. The pump according to claim 9, wherein said conical inside surface of said first upstream lip presents a cone angle that is less than or equal to 40° relative to a plane in which the circular base of the first upstream lip extends.
 11. The pump according to claim 1, wherein each of said lips is made of a material that presents a Young's modulus lying in the range 1 MPa to 220 MPa.
 12. The pump according to claim 1, wherein the first upstream and downstream lips are carried by a base that is common to those lips, which base is releasably assembled on the first wall of the chamber.
 13. The pump according to claim 1, wherein the first upstream and downstream lips are carried by said movable part.
 14. The pump according to claim 1, wherein the motor being connected to the movable part via a coupling mechanism in such a manner that actuating the motor gives rise to reciprocating motion of the movable part relative to the chamber in order to move a fluid from the suction inlet to the discharge outlet.
 15. The pump according to claim 14, wherein the reciprocating motion of the movable part is axial motion along a central axis of symmetry of the movable part, which is in the shape of a body of revolution.
 16. The pump according to claim 14, wherein the reciprocating motion of the movable part is radial motion about a central axis of symmetry of the movable part, which is tubular in shape.
 17. The pump according to claim 1, wherein said motor is an electric motor located outside the chamber.
 18. The pump according to claim 1, wherein said motor is an electric motor located inside the chamber.
 19. The pump according to claim 1, wherein the motor is connected to a control unit, the control unit being arranged to regulate the operation of the motor as a function of at least one value previously estimated by the control unit.
 20. The pump according to claim 1, wherein the pump includes a second wall of the chamber, the part being movable between the first and second walls of the chamber under the effect of said at least one motor, the pump also including a second upstream lip placed closer to the suction inlet than to the discharge outlet and a second downstream placed closer to the discharge outlet than to the suction inlet, the second upstream and downstream lips being placed between one of the sides of said movable part and said second wall of the chamber so as to define a second space between the second upstream and downstream lips, the second upstream and downstream lips being such that: over a third portion of said movement of said movable part relative to the chamber, the second downstream lip provides sealing preventing fluid from passing from said discharge outlet to said first space, the second upstream lip then allowing a free passage for fluid between said second space and said suction inlet; and that over a fourth portion of said reciprocating motion of said movable part relative to the chamber, different from the third portion of the movement, the second upstream lip provides sealing preventing fluid from passing from said second space to said suction inlet, the second downstream lip being arranged so that throughout said movement of said movable part relative to the chamber: it allows fluid to pass from the second space to said discharge outlet; and it prevents fluid from passing from said discharge outlet to said second space.
 21. The pump according to claim 1, said pump being self-priming when dry.
 22. The pump according to claim 1 wherein each of said lips is a circular lip. 